This invention pertains to shop presses having a bolster that can be locked in any one of several different vertical positions and improved cable and winch structure for accurately locating the bolster in a level position without damage to the cables.
Shop presses having an adjustable bolster with a number of different vertical positions normally include a cable and winch structure for causing movement of the bolster to the desired vertical position. A winch having two cables wound thereon which extend one to each of opposite ends of a bolster have been used whereby rotation of the winch should pay out or take up equal lengths of both cables for equal movement of both ends of the bolster. This structure has not been completely satisfactory because of tolerance variations and uneven wind of the cables which can cause problems in maintaining both the bolster ends at the same height.
Applicants' assignee markets shop presses utilizing two cables with a first cable extended between a bolster and the winch and with the second cable extended between ends of the bolster and passing over a series of intermediate pulleys. With this structure, movement of one bolster end by operation of the winch and first cable results in movement of the other end through the second cable. In such a shop press, it is possible to break a cable unless a particular sequence of operation is followed in locking the bolster ends to the side members of the shop press frame.